Controlled dashpot for fuel metering devices



Sept. 9, 1952 P. R. voGT ETAL' CONTROLLED DASHPOT FOR F'UL. METERINGDEVICES Filed July 25, 1947 5 Sheets-Sheet 1 IN V EN TOR.

Wmv WN kmq Sept. 9, V195?! P. R. voGT ETAL 2,509,662

coNTRoLLEn DAsHPoT FOR FUEL. METERING DEVICES Filed July 25. 1947 5Sheets-Sheet '2 y 2' INVENToRs,

E mi mm- F'zo/v wy/)fx BY Sept. 9, 1952 v P. R. VOGT EI'AL CONTROLLEDDASHPOT FOR FUEL METERING DEVICES 5 Sheets-Sheet 3- Filed July 25. 1947Jam 4M Sept. 9, 1952 P. R. voGT ErAL 2,509,662

` CONTROLLED DASHPOT FOR FUEL METERING DEVICES Filed July 25. 1947 5Sheets-Sheet 4 l 5 E; 5- fw L 'l I i Epu Z 7.* fvg/mf..

Sept. 9, 1952 P. R. vocsT Erm. 2,609,652

CONTROLLED DASHPOT FOR FUEL METER'ING DEVICES Filed July 25, 1947 5sheets-sheet 5 INVENTORS. iewz A11/,321,

@E @mf TMS- @oriented Sept. 9, 1952 CONTRCLLED DASHPOT FOR FUELMETERI-NG DEVICES` Paul It. Vogt, Grosse Pointe, and Paul T. Niins,

Detroit, Mich., assignors to Chrysler Corporation, Highland. Park,Mich., a. corporation of Delaware Application July 2,5, 1947, Serial No.763,576

This application relates to a control for a burner. More specificallyit' relates to controllingv a burner adapted to supply products' ofcombustion driving a gas turbine.

An object of the present invention is to provide a stabilizing means fora fuel-burning apparatus. The stabilizing means is advantageously usedwhen the fuel-burningV apparatus produceshot gases for a gas turbine,whereby the operation of the turbine is stabilized. It has beendetermined that the gas turbine should be operated at conf stanttemperature; i. e., the temperature of the gas driving theturbine'should be constant. At constant-temperature operation the`curves of turbine output torquev against speed and re-v quired torqueagainstA speed are so nearly parallel throughout much of the operatingrange that stable operation atconstant Speed is virtually impossiblewithout involving` the speed governor itself. When the turbine drives anairplane propeller, the propeller speed is governed through pitchcontrol, and so in this casev an attempt Yat stable operation willinvolve an undue amount ci propeller-pitch changing'. We propose toeliminate this drawback by providing for allowing small variations fromthe selected constant teme perature of gases driving the. turbine. lnthis Way the curve of the turbine torque against speed is caused tointersect the curve of propeller torque against speed, andstableoperationV is achieved.

without a variation beyond the speed range allowed by the propellergovernor. lThe means providing for departure from constant-temperatureoperation of the turbine may take the form of a dashpot that prevents afuel-regulating means from permitting fuel ilow to' vary With air flowfor changes in air ow of short' duration'. The dash-pot enables changesinairow of long. duration to have an eifect upon the fuel flow'.

A further object is to associate with the aforesaid stabilizing means, ameans for rendering the stabilizing means ineffective when the changeinair flow is suicient to make the speed vary from the range for whichthe governor is set.

Another object is to modify the stabilizing means in such a way that'itis ineective when there is a large reduction in air ow. In this waydanger to the turbine of too'high' a temperature is avoided, for thehigh temperatureV that would result from the greatly reduced airflow andair unchanged fuel ow is prevented by an immediate reduction of the-fuel ow' in accordance with the reduction in the air How.

Other objects will appear from the disclosure.

In the drawings:

Fig. l is a partially diagramma-tic View showing a power plant includinga gas turbine to ywhich the controlsA of the present invention are shownto be applied:

Fig. l2 is a View partially in 4section showing the application ofthecontrols oi' thev present Yin- .21 Claims; (Cl. 60g-39.28)

y vention to a fuel-and-air-metering device.; and

Figs. 36,` inclusive, show other forms' of controls of the presentinvention appliedv to a fueland-air-metering device.

Fig. l shows aV power plant for driving an airplane propeller' t); Thepower. plant comprises a compressor I-I, a regenerator I2 surrounding.the compressor, a plurality of burnersv I3', and a gas turbine It. Thegas turbine I4. is driven by hot gases producedy bythercombustionoi fueland air in the burners I`3,andfdrives the compresser` I I throughappropriate-connecting means represented by thek referencey characterI5. .The compressor il, which may beof theaxi'al. type, draws in air atitsleft end through scoops It'. Compressed air isdel-ivered D:fromtheright end of thercompressor I'I intoconduitmeans Il which lead thecompressed air to 'therregenerator' |12. The compressed air followsy azig-zag path through the regenerator I2 and isthereby heated byexhaustgasesv passing from the gas turbine It through conduit means I8 to theregenerator I2. Heated compressed air' passes4 from the regenerator I2through conduit means I9 which enclose the burners I3. Each burner isformed of aA fuel' nozzle 20 and an air tube 2l formed at anintermediate portion of nested. f-rustuin-like sections 22, which permitthe air topass through the tube wall to the nozzles 20. rllhe tubes 2Iare curved at their ends t0 directthe streams of vhot gases formed inthe burners I3 tov/jard the end of the gas turbinewl, whichisfpositioned'within the burners It. Fory a more complete showing of'the arrangement of compressor, regenerator, burners, and: gas turbine,referenceis made. to the copending application of 4Staley and Williams,Seria-1'- 4No. 715,840', dated December' 12,. 1946. For a more' completeshowing'oflthe burner tubes' 2l with the frustum--like sections`r2f2.,

reference is made to they copending application-of Samuel B. Williams,Serial No. 7 15,8731, led December 12, 1946-'.

The compressor II, which has been previously described as being drivenffrom the gas tur-bine I4 through means I5, is'drivingly connected bymeans 23 with a propeller reductiondirive which in turn drives the shaft25 on which the. propeller I0 is mounted'. ThusV they propeller .t5 isdriven fromthe gas. turbine 15j at a reducedspeed. A 'propeller .speedgovernor 2t, which includes parts responsive to' the speed* of vthepropeller 1151,v is diagrammatically illustrated as regulatingV thepropeller* pitchcontrol nie-ans- 2i throng-ha connection 28'.l f i Y fFuel Vdivider 29 is connected with the nozzles 2!v through conduits '3.Iand 32;. is fed from a gas tank 33V to .a boos-ter pump- 3,4?. thencelto a transfer pump 35i. From .the transn fer pump 35 .the fuel i'sled.by a. conduit ijgto Ya fuel-metering device 311. 'Ihencel .the fuelAprof ceeds 'by way of .a Yconduit 38 .to a tw(n1-m1111113con;Y

3 trol 39 and thence through a conduit 40 to the fuel divider 29.

The fuel-metering device 31 is responsive to a plurality of controls. Inthe conduit means I9 is positioned a plurality of elements 4| responsiveto temperature of the air passing from the regenerator I2 to the burnersI3. The temperature-responsive elements 4| exert a control over thefuel-metering device 31V diagrammatically illustrated in Fig. l by theline 42. Each air scoop I6 carries conventional elements ||5 which restsagainst a shoulder |42 on the rod |25. The various diaphragms andcollars just described are held clamped between the shoulder |42 on therod |25 and the nut |30 engaging the upper threaded end of the rod |25.The diaphragm I4| divides the fuel section into a metered-fuel chamber|43 and an unmetered fuel chamber' |44. The lower end of the rod |25 isformed as a ball |45, which is mounted in a conand I9 for measuring therate of air flow through the scoop; the air pressures acting upon theseelements are transmittedto the fuel-metering device 31.

Fig. 2 shows in detail the fuel-metering device 31 and the two-pumpcontrol 39. Reference character 4 designates a body which may be formedof several parts and through which fuel is passed for regulatingpurposes. forms part of the metering device 31. The line ||6 connectsthe velocity-pressure-sensing element ||5 withthe body I |4, the line||6 having an opening H6 to an air chamber ||1, formed in the body ||4below a diaphragm |22. impact-pressure-sensing element I I8 is shown tobe formed to be part of the body I I4 and includes apressure-compensating nitrogen-nlled bellows IISa mounted on the insideof the top of a containerv II9. Bellows |I8a contains nitrogen at somepressure dependent on conditions such as the spring rate of the bellowsand compensates for temperature and pressure. The bellows contracts withpressure and expands with temperature and therefore, assumes a positiondependent upon density, sincedensity isl proportioned to the ratio ofpressure to temperature. A valve is connected with the nitrogen bellows|I8 and is adjustably positioned by the bellows to establish arestriction in a line |208 transmitting the signal received by thepressure element IIS to an air chamber |2| formed in the body ||4 abovethe diaphragm |22, mounted within the body I I4. The pressure of airsensed by the element ||8 is transmitted to the upper side of thisdiaphragm, and the pressure sensed by the element ||5 is transmitted tothe lower side of the diaphragm. Whenever air is flowing, the pressureon the upper side of the diaphragm |22 will be greater than the pressureon the lower side thereof,vand the diiference in these pressures is ameasure of the square of the air flow. The diaphragm |22 is held betweena collar |24 and a ribbed disk washer |24a mounted upon a rod |25. Abovethe washer is a collar |23, above which is a diaphragm |26, which issecured to bridge portions |21 of the body I I4 by screws |28. Thecollar |23 and a collar |29 clamp the diaphragm |26. The collar |29 hasa recess receiving a nut |30 having threaded engagement with the rod|25. The bridge portions |21 are connected by a cover |3| which extendsover the top of the rod |25. Clamped between the diaphragm |26 and thebridge portions |21 is a guide |32 having a flange |33 in which thecollar |29 slides. The diaphragm |2'6 is retained in a flanged support|34, which is clamped to the bridge portions |21 by the screwsv |28. Thecollar |24 rests in a diaphragm |35, which closes an opening in a wall|36 dividing the body into an air section and a fuel section. Bolts |31secure the diaphragm to the wall |36. These bolts also support a guide|38 having a iiange |39 receiving a collar |40. Collar |40 holds adiaphragm |4| against a ribbed disk washer MI,

The body H4 The l necting means |455, which also mounts a ball |b on theupper end of a rod |46. The lower end of the rod |46 has a threadedportion |41 and a slot |48 for adjusting purposes. The threaded portionI 41 engages a movable inner sleeve valve |49, which is slidably mountedin a fixed outer sleeve valve |50. VThe valvesY |49 and |50 comprise anadjustable regulating valve |502. v

The outer valve |50 has an inner annular recess I5I, an outer annularrecess |52, and connecting radial openings |53. As shown in Fig. 3, theinner valve |49 partially overlaps the inner recess |5| of the outervalve so as to restrict the openings formed therein. The outer annularrecess |52 of the outer valve |50 is in registry with an annular recess|54 formed in the body ||4. The recess |54 is in communication throughmeans not shown, with a supply conduit |55. Fuel comes from the fueltank 33 to the booster pump 34, which may be of the centrifugal type.Thence it proceeds by Way of conduits |58 and |59 to the transfer pump35, which may be of the rotary sliding vane type. The pump 35 deliversfuel through the conduit to the recess |54 in the body |I4. Thence thefuel proceeds through the regulating orifice formed of the sleeves |49and |50 to the unmetered-fuel chamber |44 in the body I4 below thediaphragm I4I.

n The unmetered-fuel chamber has two outlets for fuel t-o themetered-fuel chamber |43, comprising orifices |6I and |6I.i formed in awall |63. The effective size of the orice |6| is controlled by a needlevalve |62, the longitudinal position of which is adjustable forvariation of the size of the oriiice |6I. The needle valve |62 has athreaded portion |639, which is engaged by an internally threadedportion on a gear |64, which is held against conjoint axial movementwith the needle valve |62 by a supporting means |642L which embraces thegear |64. The needle valve |62 is held against rotational movement bymeans of a square hole in the casing ||4 and a square portion on theneedlevalve, which is received by the square hole in the casing. Thegear |64 is driven by a gear |65, in turn driven by a servomotor |61'.The gear |65 also drives a gear |66 controllinga potentiometer |66. Theservomotor |61 and the potentiometer |68 are suitably connected by wireswith an amplifier |69, which is supplied by an electrical source ofpower |10. The amplifier receives a suitable electrical signal from thetemperature-responsive elements 4|, only one being shown in Fig. 2. Theneedle valve |62 regulates the fuel oriiice |6I in such a way that thesize of the orifice varies inversely with the temperature of the airsupplied to the burners, as measured by the element 4|; The signalreceived through the means 11| from the temperature-sensitive element 4|is suitably magniiied by the amplifier |69 by the electrical energyreceived from the source of power |10. Changes in the electrical signal,thus amplified cause the servo-motor |61 to rotate the gear |65.Rotation of the gear |65 is effective by way of the gear |64 to providelongitudinal adjustment of the needle valve |62 Vand thereby adjustmentof the fuel orice |6|. Rotation of the gear |95 is also effective by wayof the gear |66 to adjust the potentiometer |68 tc restore the entireelectrical apparatus to balance. In other words, with the change inelectrical signal, the servo-motor |61 will operate to rotate the gear|65 indefinitely unless compensation is provided in an adjustment ofresistance, and this is done through adjustment of the potentiometer |63by the gear |66.

The fuel orifice |6|a is regulated by means of aA longitudinallyadjustable needle valve |13, to which is connected a pivotally mountedindicator |14, having a point moving along suitable indicia- |15,representing desired temperature of combustion products delivered by theburners to the gas turbine. The indicator |14 and needle valve |13 areshown in a mean position. Movement ofthe needle valve to the left,produced by clockwise angular movement of the indicator, increases theeffective opening of the fuel orifice |6| and thereby increases thetemperature to be reached by the products of combustion of the burnersgoingA to the turbine. Movement of the needle valve |13 to the rightproduced by counterclockwise angular movement of the indicator |14 willdecreasev the effective opening of the fuel orifice |6|a and therebydecrease the temperature of the products of combustion produced by theburners.

The fuel chambers |23 and |44 above and below the diaphragm |l|| areplaced in communication by a passage |16 formed in the body lili andhaving a .restriction |11. Similarly, the air chambers ||1 and |2| areplaced in communication by a passage |18 formed in the body Hd andhaving a restriction |19. The metered fuel chamber |23 is incommunication with a chamber |19EL for fuel formed by the cover |3|, thebridge portions |21, and the diaphragm |26. Communication is establishedthrough a passage |36 formed in the body H4 and having a restriction |8|at the end adjacent the chamber |19. A passage |82 connects the chamber|193 with a chamber |63, formed below a diaphragm |84 carrying aprojection 89 limiting the lower position of the diaphragm |34. Abovethe diaphragm |89 is a chamber |86, which communicates by a line |81with the unmetered fuel chamber! 44 through an opening |99. The chamber|33 is connected with a chamber 89 positioned below the wall |99 havingan orifice |9| closed by a valve |92, as

shown in Fig. 2. Above the wall |99 is a chamber |93, which communicatesthrough a line |99 with the metered-fuel chamber |43. The top of thechamber |93 is formed by a diaphragm |95, which is connected to the stemof the valve |92 and prevents fuel from going from the chamber |93 intoa solenoid |96. The solenoid |96 controls the valve |92 through aplunger |91, secured to the stem of the valve |92 in axial alignmenttherewith. The solenoid |96 is supplied by wires |96EL and |96b from asource of electrical power |969. Between the wire |96a and source |96cis connected a speed-responsive switch, which com-r prises spacedterminals |96d and |969, connectedto the line |9621, and a contactor arm|961, controlled by a means |995 responsive to turbine speed. Morespecifically, the means |96g may be associated with thepropeller-pitch-control governor. Propeller speed is directlyproportional to turbine speed. The propeller is normally constructed sothat a certain pitch produces a given speed range of propeller.Different speed ranges may be preselected, and thus a position of thearm |96 between the contacts |96d and |96@l may be produced by differentselected speed ranges.

6l The larrangement is 'such` that, when the turbine is operating in thedesired speed range, the con-V tactor |96f is positioned-between theterminals |96d and |96e and outv of contact with each of them so thatnocurrent flows to ther solenoid |99.

Under this condition, fuel pressure acting up-- wardly against thediaphragm |95 causes the 'the plunger |91' downward to a centralposition and opens the valve |92, placing the chambers |99 and |93 incommunication. A spring |98 acts against the plunger v|91'to urge itdownwards and thereby provides compensation for a fuel pressure in thefuel chamber |93. The space above the diaphragm |93 is vented by anopening |965. YThe air chambers ||1 and |2| are connected by a passage|99, which is shown to be closed by a valve 266. A spring 29| isconnected at its yright end to the body H4 below the diaphragm la! inthe unmeteredefuel chamber |99. The left end of the spring 29| isengageable with a flange 292 formed on the connecting means |99ab so asto provide a yielding limit to upward movement of the stems |29 and |96and a minimum opening of the regulating orice |593, formed by the valves|49- and |59. A rod 262e slidably mounted in the body ||4 may be movedupwardly from the position shown to lift the spring'26l and thereby toremove the lower limit on the size` of the regulating orifice |59a. A

' threaded member 262|, mounted in the body H9,

provides an adjustable stop engageable with the spring 26| so as todetermine the position the spring will assume when the rod 262a is outof the way, as shown in Fig. 2. A removable cover 292c protects thethreaded member 29210. The fuel chamber has a drain plug 263.

A fuel line 29d extends from a region of the metered fuel chamber |93immediately to the left of the fuel orifices |9| and |9|a. The line 269splits into branches 295A and 266, which lead to pumps 291 and 268,which maybe of the gear type. A relief line 269 is connected to oppositesides of the pump 201 and contains a relief valve 2HE. rShe pump 291discharges through a line 2H and a check valve 2|2 from which lead lines2|3 and 2M. The line 2|!! is formed into two branches ZIE and 2|6. Thelatter line leads through a valve 2|1 to a flow divider 2|9 from whichseparate lines go to in dividual burners. rThe line 2|5 forms part of abypass for pump 291 and leads to a valve 2|9 formed of a body 229, asleeve y22| positioned therein, a cover 222 and a balanced piston valve223 slidable within the sleeve 22|. The line M9 leads directly to anannular recess 221| formed in the body 229 about the sleeve 22|. Theannular vrecess 225| communicates with the space between sections-225and 226` of the piston valve 223 by way ofipassages 22.1 formed in thesleeve 22|.` Passages-228 in sleeve 22| provide communication from thespace between the piston valve sections 229 and 226 and a drain line 229leading. back to the line 296. The drain line 229 carries a float valve239 for eliminating from the line any trapped fuel vapors. The pump 298is provided with a relief line 23|. which is connected to. oppositesidesv of the pump and carries a relieffvalve232.A .Aponduit 233 leadsfrom the discharge side of the pump 208 and separates into two branches234 and 235. The branch 234 is connected by a check valve 236 with thebranch 213 associated with the pump 267. The branch `235 leads to thevalve body 22B and communicates with the chamber between the pistonvalve sections 225 and 226 by means of openings 23'1 formedin the sleevevalve 22|. The space above the piston valve 223 is connected by a line238 with the conduit 204 and subjects the top side of the piston valveto the fuel pressure in the line 264. A coil spring 239 acts againstvthe top of the piston valve 223 to urge it downwardly. An extension 246formed on the top of the piston valve 223 limits upward movement of thevpiston valve. A short extension 241 formed on the lower side of thepiston valve 223 limits its downward movement. The space below `thepiston valve 223 is connected by a line 242 having a restriction 243 tothe discharge side ofthe transfer pump 35. Fundamentally, the controlvalve 219 for the pumps 201 and 268 operates from the difference inintake and discharge pressures at the apparatus included in body 114,for the upper end of piston valve 219 is subjected to the dischargepressure of the apparatus existing in line 264 and the lower end of thepiston valve is subjected to the intake pressure of the apparatusexisting in line 155 as communicated by line 242. Restriction 243removes the effect of variations of intake fuel pressure of shortduration and also dampens oscillations of piston valve 219 from othercauses. Spring 239, acting on the upper end of the piston valve 223assures that the piston valve assumes a certain position along thelength of the valve sleeve 221 for a given difference in intake andoutlet fuel pressures as transmitted to the ends of the piston valve. Y

A return line 244 leads from the line 2|6 to the conduit |59 ontheintake side of the transfer pump 35. Communication between the lines 216and 244 is regulated by a piston valve 245 under the control of a speedgovernor 246 responsive to turbine speed. A relief line 246a containinga relief valve 241 connects the intake and discharge sides of thetransfer pump 35. A line 248 leads from the line 244 to the valve 2|?.A. drain line 249 is connected to the valve 21'i. During normaloperation the valve 21'1 passes fuel from 'the line 216 to the fueldivider 218. The valve is so constructed that when appropriatelyregulated, it connects the flow divider with the line 249 for drainingthe former and lines 216 and 248 for passing the entire flow of fuel tothe discharge side of the transfer pump 35.

In operation of the above described apparatus, fuel is drawn from thefuel tank 33 through the booster pump 34 through conduits |58 and |59,the transfer pump 35, and the conduit 155 to the body 1 14, throughwhich it passes to the annular recess 154 and thence through the orifice153 and annular recesses |51 and 152 in the outer fixed sleeve valve |56and past the upper edge of the movable inner sleeve valve 149 to theportion of the unmetered-fuel chamber 144 below the diaphragm |4I. Fromthere thefuel moves to the metered fuel chamber 143 to the left of wall163 by way of the orifices 161 and 161B, the sizes of which areregulated in accordance with temperature of air going to the burners, asmeasured by the element 4|, and by desired temperature of products ofcombustion going from the burners to the gas turbine, as predeterminedby an appropriate Vsetting of the indicator 114. The orifices 161 and|61a jointly constitute metering orifice means, and the pressure of thefuel is reduced in accordance with the amount of restriction provided atthese orifices by the needle Valves 162 and 113, which adjust theorifices. Since the unmetered-fuelpressure is greater than themetered-fuel pressure, the diaphragm 141 will be lurged upwardly with aforce dependent upon the difference 'between these two fuel pressures,which difference is in turn dependentI upon the square of the flow offuel past the orifice 161 and 161e. The upward net force throughfuel-pressure difference acting upon the'diaphragm 141 is communicatedto the rod 125. This upward force on the rod is opposed by a downwardforce on the rod dependent upon the difference in air pressures actingupon the upper and lower sides of the diaphragm 122 in the air chambers11"| and 12| and transmitted thereto from sensing elements and |18. Whenthe flow of fuel is proper for the iiow of air, the air-pressuredierence acting downwardly upon the diaphragm 122 is effectivelybalanced by the fuelpressure difference acting upwardly on the diaphragm141. Thus the Valve 149 holds its position, and there is no change inthe size of the regulating orifice formed by the valves 149 and 156. Letit be assumed, for the moment, that the Valve 192 is open. If the flowof air to the burners changes in rate, this change will be sensed by theelements 115 and 118, and a changed difference in pressure will betransmitted to the diaphragm 122. If the rate of air now increases,there will be a greater air pressure difference acting downwardly uponthe diaphragm 122, and for the moment the upward fuel-pressuredifference acting upon the diaphragm 141 will be effectively less thanthe air pressure difference acting upon the diaphragm 122` As a result,the rods 125 and |46 will move downwards causing the upper end of themovable sleeve valve 149 to provide less of a restriction to therecesses and passages in the outer fixed valve 1511. Thus there is anincrease in the size of the regulating orice, and consequently, the iiowof fuel increases. Since the fuel now increases, the drop in pressureacross the orifices |61 and 16| increases, and thus there is provided agreater fuel pressure difference acting upwards upon the diaphragm 1 4 1When the increase in fuel-pressure difference effectively matches theincrease in air-pressure difference, downwardmovement of the valve rods125 and 146 and of the inner sleeve valve 149 ceases. Thus Aa new fuelfiow has been established, which is appropriate to the new increased airflow. If the air flow decreases, the opposite of the above describedtakes place. The effective force of the fuel pressure difference actingupwardly upon the diaphragm 141 is greater than the eective force of theair pressure difference acting downwardly upon the diaphragm 122, andtherefore, the rods |25 and 146 and the inner sleeve valve 149 moveupwardly. This action decreases the size of the regulating orifice|51!EL formed by the valve parts 149 and 150, and the fuel nowdecreases. Thus the fuel-pressure drop across the orifices 161 and 16|ais decreased, and a lower upward pressure acts against the diaphragm141. Thus balance is restored between the air-pressure difference actingon the diaphragm 122 and the fuel-pressure difference acting on thediaphragm 141.

y During the above described changes it has been presumed that the valve192 was open, and this lflow rate.

was the case if the turbine was noi-l inthe de.- sired speed range, sothat the solenoidv was electrically 'energized to bring the coreV |97vto its lower position. 'Let it now be assumed that the turbine isoperating in 'the-desired'speed range. Now the solenoid V|98 is nollonger energized, and the plunger is? brings the valve |92 to closedposition under the influence of thefuel pressure acting upwards'againstthe diaphragm |95.- Now fuell in the chamber l'iEL annotescape by way ofthe line H72, chambers |83 and |8i, orifice |9|, chamber |93 and lineist, and the only outlet from the chamber Ilse is through the passage|80, but this passage has the restriction |8i, which provides a timedelay to such escape. Thus the volume of fluid in thechamber |79a cannotchange suddenly, and the diaphragm |26 cannot shift its positionsuddenly. Consequently, the rods and |45 and the inner sleeve valve |49cannot immediately move upwardly or AYdownwardly in response to changesin air flow as transmitted as a pressure difference to the diaphragm|22. The rods and 'valve |49 can move only if there is sufficient timefor fuel to flow through the restrictedlorice |8| into or out of thefuel chamber |79@ Thus changes in air flow of a short-duration have noeffect upon the fuel ilcw, for temporarily the innersleeve valve |49Vremains in its original position, and there is no change in the size ofthe regulating orice. Keeping the fuel apparatus from being sensitive toair-flow changes of a short duration prevents unstable operationof theapparatus, which may easily occur if the controls are made sensitive tochanges of a short duration inthe use of the apparatus with the powerplant shown in Fig. 1.

If the air flow decreases sufficiently, the rod |25 will be urgedupwardly with sufficient force to cause the compression of the trappedfuel in the chamber |Ti|a to act against the diaphragm |84 sufciently tolift it and thereby to provide the appropriate increase in space for thetrapped fuel to permit the upward movement ofthe rods |25 and |46 andthe inner sleeve valveA It for reduction of the regulating orifice.Lifting of the diaphragm |86 takes place when the pressure in thechamber |79@ has through compression risen from metered fuel pressure upto or just above the unmetered-fuelpressure existing'above the diaphragm|54. Thus for a large reduction in air flow there will be immediatelyprovided an appropriate reduction of fuel flow as a precaution againstoverheating of the turbine dueto too high a temporary rate of fuel-flowrate to air- The fuel ow will not immediately be reduced completely totheA point Vwhere vthe ratio of fuel to air flow is the predeterminedvalue, because this ratio can be obtained only when the pressure in thechamber |79a is the same as that in chamber H7, and this pressure willbe equal only when sumcient fuelhas escaped from the chamber |793, andthis requires time. The error represented by the difference between thefuel flow actually existing under this condition and the theoreticallycorrect fuel now for the actual air flow will be always approximatelythe same percentage of the fuel flow, since the diaphragm |813 issubjected to the difference between metered and unmetcred-fuelpressures, which is a measure of fuel flow. A large increase -in air owwill not immediately have the same effect, because the resultantincrease in downward thrust upon the air diaphragm |22 will only tend toincrease the volume of fuel trapped against immediate release from thespace |79il and associated parts. This 10 will tend to move thediaphragm |84 downwards to achieve compensation by reduction of the sizeof the chamber |83, but 'the' projection |85; atu tached to thediaphragm prevents downward movement of the diaphragm.-

Under starting conditions, it may be desirable to use a lower rate offuel ow than lmay be allowed-by the minimum position established by Vtheidle spring 20|.

In this event, the rod 2|l2a is pushed upwards tov raise the spring 20|and thereby to permit the inner sleeve valve |49 to move upwardsinresponse to the air-pressure difference arising from low air flow andthereby reduce the regulating orifice to make possible the new desiredminimum fuel flow. At other conditions it may be desirable to have aconstant fuel flow, for example, a minimum now permitted by the return of the idle spring 25| to the position shown in Fig. 2, regardless of theair conditions measured by the elements ||5 and |1|'8.

the temperature-responsive element |12 has not acted through variousdescribed control means to adjust theflongitudinal position of the'needle valve |62. to the burners increases, the needlevalve |62 ismoved to the right, reducing the. effective size of the orifice lti.This means a greater restriction of the fuel flowing past the orificesandconsequently, a lower fuel-flow rate for a given 'pressure dropacross the'orice. As thels'ize'of Ythe orifice itl is decreased, thepressure ldrop may, for the moment, :increase and this produces anupward movement of the rodsA |25'and |46 and the valve |49. Thus'thereis a reduction inflow through the regulating orice formed of the valveparts-|55 andV |5I, and this reduction in flow brings about a reductionkin pressure difference across the orifices |6| and ||5|a to obtain areturn of the original fuel pressure difference acting on the diaphragm|4| to match the airpressure difference acting on the diaphragm |22.Thus the rate of air vflow has remained the same, Vbut the rateof fuelflow has beendecreased as the temperature Vof air flowing to the burnershas increased. Thus the ratiol of fuel toair has decreased, wherebythereis provided asuitable balance for the` increase of air temperaturein maintenance of a constant temperature of products of combustionleaving the burners. Decrease inthe temperature of air owing to theburners has the opposite effect. the needle valve |62 moves to the leftincreasing the effective opening of the orificel ISI Thus therestriction ofthe flow of fuel across orifices |6| and Iia is decreased,and there may be a similar pressure drop across these orifices. Thedecrease in pressure drop is transmitted to the diaphragm |4I, whichvnow receives less force tc oppose the force applied by air pressuredifference to the diaphragm |22, and the rods |25 and |65 and the valvesleeve |49 may move downwards to increase the size of the regulatingorifice formed by the valve sleeves` |50 and |`5|. This produces anincreased vfuel flow, increasing the 'pressure drop across thecrices Iciand |611@L to `restore balance between the fuel-pressure forces If nowthe temperature of air going In this case,

11 acting against the diaphragm |4| and air-pressure forces acting ondiaphragm |22. Thus the air-flow rate has remained the same, while thefuel ow rate has increased, and so there has been provided an increasein the ratio of fuel flow to air flow. Thus there is provided acompensation for the decrease in the temperature of air flowing to theburner in maintenance of a constant temperature of products ofcombustion y flowing from the burners to the turbine.

If a greater temperature is desired for the products of combustionpassing from the burners to the turbine, indicator |14 is moved to aclockwise direction thereby moving the needle valve |13 to the left andincreasing the effective size of the orifice |6|a. Thus, for the moment,the pressure drop across the orifice is reduced for the flow of fuelremains constant, and the fuel-pressure difference acting upwardlyagainst the diaphragm |4I is reduced. Thus the balance betweentheair-pressure forces and the fuel pressure forces is disturbed, andthus sleeve valve |43 moves downwardly increasing the regulating orilice1 formed between the valves |49 and |50. This increases the fuel flowand the pressure drop across the orifices |6| and |6Ie. Thus balance isArestored between the diaphragms |22 and |4.|.

The air-flow rate has remained the same, and the fuel flow rate hasincreased. Thus there is an increase in the ratio of fuel flow to airflow, and since the temperature of air flowing to the burners has beenassumed to remain constant, the increase in ratio of fuel to air mustresult in a greater temperature of products of combustion produced bythe burner. Similarly the temperature of products of combustion may bereduced by greater restriction of theorice |6|a by the needle valve|13.`

After the fuel passes through the metering orices |6| and |6|e, it goesthrough the conduit 204 to the pumps 201 and 208. If the pump 201 isfunctioning properly, the entire output of the pump 208 will bebypassed, with the parts in the position shown in Fig. 2, through theopenings 231, the space between the piston valve sections 225 and 226,the sleeve openings 228, and the return line 229 back to the intake sideof the pump 208. A portion of the output of the pump 201 will bebypassed through the line 2 l5, the sleeve openings 221, the spacebetween the piston valve sections 225 and 226, the valve sleeve openings228, and the return line 220 to the intake side of either pump 208 orpump 201. The portion of the pump 201 that is not bypassed as aforesaid,is delivered through the line 2|6 and the valve 2 |1 to the iiow divider2 I8, whence it proceeds to the individual burners. The position of thevalve 223 will determine the relative portions of the output of the pump201 that are bypassed through theline 2 l5 and delivered to the burnersthrough the line 2 I6. The position of the valve 223 is determined bythe pressure of fuel above the valve piston section 225, which isdetermined by the difference between the pressure existing in the line204 leading to the pumps 201 and 2 8 and the pressure in line 242, withthe aid of a coil acting against the valve piston section 225. The forceinserted by spring 230 is substantially constant in all positions and isadapted to balance a difference in pressure normally always existingbetween line 242 and line 204. If it be assumed that the pressure inline 242 is constant, and this is generally the case, then the greaterthe pressure in the line 204, the lower the position of the valve 223,the more the piston valve section 225 covers the ports 221, the less theamount of output by the pump 201 bypassed through the line 2|5 and thesleeve valve openings 221, and the greater the amount of the output ofthe pump 201 going through the line 2 |6 to the flow divider 2|8 and tothe openings. Thus there is a tendency to maintain the constant pressurein the line 204 or on the intake side of the pumps 20? and 208, for thegreater this pressure becomes, the greater the relative amount of thepump output delivered to the burners. If pump 201 fails, presumably theoutput pressure of the pump falls very low, and the fuel pressure on theintake side reaches a high level. Consequently, two things happen: pump208 delivers fuel through line 234, check valve 236, and lines 2|3, 2|4,and 2i6 to the iiow divider 2|8; and the piston valve 223 is depressedunder the increased fuel pressure in the line 204 until the sleeve valveopenings 221 are completely closed, and the sleeve valve openings 231are at least partially closed, thereby reducing the amount of fuelbypassed from pump 208 by way of line 235 and return line 229. If pump201 again functions properly, pressure in the line 204 will besufliciently lowered as a result of fuel delivered by pumps 201 and 208to cause the piston valve 223 to rise until the output of pump 208 isbypassed by virtue of complete uncovering of the valve openings 231, anda portion of the output of pump 201 may be bypassed by a partialuncovering of the valve openings 221.

Fig. 3 shows a modified form of fuel-metering device 31a. Like themetering device 31 of Fig. 2, the present device 31e includesair-pressuresensing elements ||5 and ||8, and air diaphragm |22, onopposite sides of which are air chambers |2| and ||1, a fuel diaphragm|41, on opposite sides of which are a metered-fuel charnber |43 and anunmetered-fuel chamber |44, and a regulating valve |50, comprising anouter valve part |50 and an inner valve part |49, regulated by the airand fuel diaphragms |22 and |4| through rods |25 and |46. Thefuel-metering device 31e is supplied by a transfer pump |50 which is inturn supplied by a booster pump |51, which receives fuel from a tank|56.

The body of the metering device 31a has an interior wall |63 carryingmetering orifices |6| and lle. The orifice |6| is controlled by a needlevalve |62, which is adjusted in longitudinal position for adjustment ofthe sides of the orifice I6 l, by a thermostatic element 250 operatedfrom the temperature-responsive 4|. The needle valve |62 carries ashoulder 25|, which is engageable with a stop 252 to limit the leftwardmovement of the needle valve |62 and thereby the size of the meteringorifice |6|. The element 4| is responsive to the temperature of airtraveling from the regenerator |2 to the burners I3, and therefore, theneedle valve |62 is adjusted to make the size of the metering orifice|6| vary inversely with the temperature of the air traveling from theregenerator to the burners. The size of the orifice |6|a is controlledby a needle valve |13. manually settable by a pivoted indicator |14moving along suitable indicia |15. The longitudinal position of theneedle valve |13 predetermines, as designated on the indicia |15, thetemperature of the gases delivered by the burners |3, all as in Fig. 2.

The metering device body of Fig. 3 carries bridge portions |21, whichsupport a cap |3| and a diaphragm |26 and form therewith a chamber |19afor fuel. The metering device of Fig. 3 differs from that ofFig. 2 inthat apassage-253 leading from the chamber H6@- through the re'- st-rietion IBI leads -to the unmetered f uel vchamber idd below the fueldiaphragm UH, rather than to the imetered fuel chamber. Anunrestricted-passage 252 leads from the :fuel chamber H92 to acylindrical opening 255 in which is re- Apassage 25? Ciprocally mountedVa piston 256. 1leads from the cylindrical opening r255 on the sideopposite the passage 25!! -to a chamber-|63 Vwith a diaphragm 259,subjected labove and below through the Vline 268 and 26| to the airpressures existing in the air chambers El? and I2I, below and above theair diaphragm |22. The diaphragm 2,53 urges the piston 255 upwards witha force vindicative of the air flowing to the Y burners. A passage 26|leads from the intermediate portion of the cylindrical opening 255 to apassage 262 leading from the .chamber |89 to the unmetered-fuel chamberldd. A projection 263 is formed in the base of the cylindrical opening255. The relief passage 265i leads from the base of the cylindricalopening 265 lto the passage 26 I. Fuel is delivered from the meteringdevice 3l.av ofFig. 3 through a conduit 264 lto a two-pump system 39like the one in Fig. 2 and thence to the flow divider 2 I 6.

The general operation of the devices @la of Fig. 8 is like that of thedevice Sl of Fig. 2. Ifuel reaches the device 32a from the transfer pump|62 upward of the conduit |55. The regulating valve |52a determines theamount of fuel flowing and is adjusted by the air diaphragm |22, whichis responsive to the amount of air flowing, and the fuel diaphragm IfIwhich is responsive to a drop in fuel pressure across the meteringorifices |6| and |69. When the gas turbine |45 or the propeller I0 isnot operating in a predetermined speed range, the solenoid |96 causesthe plunger |92 t0 occupy a central position, thereby causing the valve|62 to open the passage lill. Under these conditions, when the air andfuel diaphragms |22 and ltI move the inner valve part |29 up or down tomaintain a predetermined ratio of fuel-flow rate to air-now rate, thereis no interference to such movement of the diaphragms and inner valvepart Idil offered by the .chamber |162, `for fuel Vmay enter or leavethe chamber ile@ freely by way of the opening I9 I.

However, when the turbine or the propeller is operating in a desiredspeed range, the effect on the solenoid |26 is such as t0 bring theplunger i9? to the displaced position of Fig. 3 and the Valve |92 to theposition of Fig, 3 in which it closes the opening |9I. Now fuel canenter or leave the chamber |79a only by way of the passage 253 with itsrestriction ISi. Since the entrance or exit of fuel can take placethrough the restriction I8| only slowly, the diaphragm |26 forming onewall 0f the chamber I'iamoves only slowly and permits the inner valvepart |119 to move only slowly. Thus the inner valve part Hi8 is notsensitive to any air flow changes 0f short duration, which would imposechange in forces of short duration acting upon the air diaphragm |22.

Assume now vthat thereis Va large reduction in air flow. This willresult in a large reduction in theznet .downward force .of air actingupon the air diaphragm |22. This willcause the fuel forces to purge the.fuel diaphragm IM upwardly, resulting in an attempted compression-of'the fuel contained in the volume composed of chamber H2, lines 1254:and 25.7, the space in cylindrical opening'12'55 above piston 256,.andchamber |93. Since the decrease in air pressure difference acting luponthe air ydiaphragm |22 is large, the compression of the fuel containedin the aforesaid volume vincluding the upper part of the cylindrical.opening 255 `will be large, and when it is large enough to .overcomethe upward forces on thepiston 256 imposed thereon by the diaphragm 259in response to the amount of :air flowing, the

piston 256 willfmove downwardly to allow.escape `ofthe compressed fuelthroughthe passages Ztl and 262 to the unmetered fuel chamber |62. Sincefuel `can nowescape from the chamber lille and associated passages and.chambers upward of the 'lines 26| Vand 262, the diaphragm |26 may moveupwardly and with :it the inner valve part |49, kreducimg; thefuel nowin conformance with the greatlyreduced air flow. Reduction in fuel flowvin response to a large reduction in air flow.

is provided so that the turbine will not overheat because'of too higharatio .of fuel Yto air in the burners. `It will be understood Athatwhile the volume fincluding the chamber |19, the passages 252 vand 251,the chamber |93, .and the space .above the `piston 256m the cylindricalopening 255 `is undergoing compression sufficient .to depress the piston256 .to allow escape of fuel from the aforesaid Volume by way ofy thelines Ztl and 2 62, and the fuel ow'rateis being reduced thereu by in'conformance with reduction in air-'flow rate, the fuel-*now .rate `willnot be reduced sufficiently to provide the predetermined ratio offuel-now rate to air-flow rate for which the metering orifices 16| and|6|a are set, for the refn lease of compressed fluid by way of thepassages 26| and 262 can be eected only when the huid in the chamberIItla is under compression, and yet the opposition `provided by way ofcompres sion in the .chamber |19@L will prevent the inner Valve part |69from reaching the position requisite for maintenance Yof thepredetermined ratio of air-flow rate to fuel-flow rate. l Under theseconditions the error kbetween the actual fuel-*flow rate and atheoretical fuel-flow rate matching the greatly reduced air-flow rateand maintenance of the predetermined ratio of air to fuel will be asubstantially constant percentage of the amount of fuel flowing, for theupward air force on the diaphragm 259 acting through the piston 256 toprevent release of the compressed fuel in the chamber |79a by way of thepassages 26| and 262 is proportional to air flow and in turn to fuelflow and determines the amount of error between actual fuel flow andtheoretical fuel flow. f

When the air how increases a great amount, there is no need for a suddenappropriate :lncrease in fuel now, since the temperature of the turbinewill decrease rather than dangerously increase, because of reduction infuel to air ratio. Greatly increased air flow will cause the airdiaphragm |22 to attempt to move downwards, attempting to bring thediaphragm |26 downwards and to increase the volume of trapped fuelincluding the chamber I'Ia. This attempted Volume increase will move thepiston 256 up slightly, but will provide no opening of the pas- V 15sage 26| for entry of fuel to match the attempted volume increase.

Reference has been made in the next to the last paragraph to the factthat the diaphragm 259 responsive to air forces indicative of air iiow,urges the piston 256 upwardly and thereby provides an error betweenactual fuel flow and theoretical fuel iiow under a condition of greatlyreduced air iiow. Fig. 4 shows a modified device in which the diaphragm259 is subjected to metered fuel pressure and unmetered fuel pressure byway of lines 265 and 266 connected with the fuel chambers |43 and |44.In this modification the upward force imposed upon the piston 256through the diaprhagm 259 is proportional to fuel flow rather than airiiow, but the result is approximately the same.

In Fig. there is shown a third modified form of fuel-metering device,Vwithy which there are associated, as is the case with metering devices8'! and 31a of Figs. 2 and 3, air iiow measuring elements |I5 and H8, anair diaphragm .|22, on opposite sides of which are air chambers |I1 and|2I, a fuel diaphragm |4|, on opposite sides of which are fuel chambers|43 and |44, and a Wall |63 in whichv are formed metering orifices I6|and |6I1. The orifice IGI is adjusted in size by means of a needle valve|62, which is controlled by a thermostatic element 258 responding totemperature measured by the element 4| of the air flowing from theregenerator I2 to the burners I3. Thus the orifice |6I is made to varyinversely with the temperature of the air flowing fromthe regenerator tothe burners. A shoulder 25| formed on the needle valve |62 engages astop 252 to limit leftward movement of the needle valve |62 and therebythe amount of opening of the metering orifice |6 I Longitudinaladjustment of the needle valve |13 through an indicator |14 moving alongappropriate indicia |15 adjusts the predetermined temperature ofproducts of combustion delivered by the burners I3 to the turbine I4.The less the metering orifice |6|a is restricted by the needle valve|13, the greater the aforesaid predetermined temperature of products ofcombustion. The air and fuel diaphragms |22 and |4| are connected with arod 261, which carries at its right end a regulating valve 268controlling the size of a regulating orifice 269, which provides anopening for fuel from a receiving chamber 218 formed in thefuel-metering device 31b to the unmetered fuel orice |44.

The metering-device 31b of Fig. 5 differs principally from thepreviously described metering devices in that the metered' fuel chamber|43 may be blocked or restricted to provide the desirable delay toresponse of the fuel-flow rate of short duration. An extension 21| ofthe wall |83 is provided with a passage 212 having a restriction 213. Avalve 214 is shown in Fig. 5 to be blocking unrestricted escape of fuelfrom the metered fuel chamber |43. The valve 214 is controlled by aplunger 215 formed as an eXtension of the valve 214 and operating underthe iniiuence of solenoid 216 and a spring 211. When the turbine or thepropeller is operating in the desired speed range the valve 214 is inclosed position, as shown in Fig. 5, so that escape or entrance from orto the metered fuel chamber |43 is had only by way of the restrictedpassage 212. Fuel trapped in the metered fuel chamber |43 providesresistance to any attempted movement of the regulating valve 268occasioned by changes in air-flow rate. The changes in airflow rate willbe effective to change the fuelflow rate only if they last long enoughfor the fuel to enter or exit slowly through the restricted passage 212.The operation of the solenoid 216 on the valve 214 is reversed from theoperation of the solenoids of Figs. 2 and 3 with respect to theirvalves. The valve 214 is in closed position when current flowing to thesolenoid 216 causes the plunger 215 to occupy a central position, asshown in Fig. 5. This requires an electrical circuit somewhat modifiedor reversed from that shown in Fig. 2, but it is believed unnecessary toshow such circuit, since it forms per se no part of the presentinvention.

Fuel is delivered from the metering device 31b through a line 284 to atwo-pump system 39 like the one in Fig. 2 and thence to a flow divider 2I8.

In Fig. 6 there is a fuel-metering device 313, which is somewhat similarto those of Figs. 2 and 3, but differs slightly therefrom. The device ofFig. 6 includes air-measuring elements ||5 and 8, an air diaphragm |22,on opposite sides of which are air chambers ||1 and |2I, a fueldiaphragm 52| on opposite sides of which are fuel chambers i 43 and |44,and a regulating valve |58 formed of a movable inner valve part |49 anda stationary outer valve part |56. The air and fuel diaphragms |22 andI4| act through rods |25 and |46 to control the position of the innervalve |49 in maintenance of a predetermined air-to-fuel ratio. Fuelpasses from a gas tank |56 to a booster pump |51, thence to a transferpump |60 and thence by way of a conduit |55 to the fuel-metering device31C. The device contains an inner wall having metering orifices F5! andIla. The orifice i6| is adjusted to vary inversely with temperature orair flowing from regenerator |2 to the burners I3 and the orice I 6|a isadjusted to vary directly with the desired temperature of products ofcombustion flowing from the burners I3 to the turbine I4. The body ofthe device 31c has bridge portions 21 which carry a cap |3| and adiaphragm |26 and forms therewith a chamber |193 for fuel. A passage 218having a restriction 219 at the end adjacent the chamber |19EL leadsfrom the said chamber through one bridge portion |21 to the unmeteredfuel chamber |44. A passage 219 leads from the chamber |19HL through theother bridge portion I 21 to a chamber 280, of which the top is formedof a diaphragm 28|. An opening 281 connects the chamber 286 with achamber 283. The chamber 283 has an upper wall 284 provided with anopening 285 shown closed by a valve 286. One end of the rod of the valve286 is formed as a plunger 281 controlled by solenoid 288 and a spring289. Formed between the wall 284 and a sealing diaphragm 298 is achamber 28|, which is connected by a passage 282 with a chamber 29Sformed above the diaphragm 28|. The solenoid 288 is adapted to becontrolled by means similar to that shown in Fig. 2 for controlling thesolenoid i 96. Fig. 6 shows the valve 286 to be closed when the plunger281 is in raised or displaced position because of the pressure of thefuel in the chamber 29| acting on the diaphragm 298. The valve andplunger are so positioned when the turbine or propeller is operated in adesired speed range and at this time the solenoid 288 is not energized.When the turbine cr propeller is not being operated in the desired speedrange, the solenoid is energized to lower the plunger 281 and valve 286.A coil spring 294 acts between a wall 295 and the diaphragm 28| to urgethe diaphragm downwards. Downward movement of the diaphragm 28| islimited to the position shown in Fig. 6 by .aeoaeea flow, lthe-innervalve part1w|49rof the regulating valve FifiEL maymove upwards ordownwards to adjust the fuel flow, in-maintenance ofa predeterminedratio of. air-now rate to fuel-flow rate. Fuel in the chamber |19EL isnot forced to escape or enter the chamber 'I1-9a by way of therestriction 219 and the passage 218, butmay escape or enter by way ofthepassage 219, chamber 28|),v passage 281,. chamber 283, opening285,chamber 29|,y and line 298 connecting the chamber 29| and the unmeteredfuel chamber |44. vUnder these conditions the fuel-flow rate is`adjusted immediately in response rto changesin air-flow rate even ,ofshort duration. When the turbine or propeller is operating inthe desiredspeed range, the valve 28E closes the opening 285, and now vfuel in thechamber I1'9ais forced to escape or enter by way of the restriction 219.Thus the responsiveness of the inner valve part 249 to changes inair-flow rateis slowed, and the fuel-flow rate iskept constant in spiteof changes in .air-now rateof short duration.y VIfl the air-flow ratevis reduced a large amount, the reduction. in downwardforcefacting uponthe air-.diaphragm |22 will allow Vthe .com tinuing upward force upon.the fuel ldiaphragm lill to attempt to move the inner valve part |49and the diaphragm |25 upwards. .The result is .a compressionrof the fuelin the container or volume formed of the chamber |192 the passage 21.9,the chamber 280, the opening 281 and: the

chamber 283. Since thepupward force on the di- .to thelarge'reductionVin air flow. 'I'his :arrangement prevents the turbine from beingoverheated ,because of a Atemporary excessive air-fuel ratio.

If there is a largeiincrease in air now, there is not an immediate largeincrease in fuel ow, and

there Iisno need for suchincrease in fuel flow,

because the resultant reduction in air fuel ratio aphragm |26 `couldmove downwards immediately only if the diaphragm 23|`cou1d movedownwards immediately, and this is impossible, as previously stated. jFuel is delivered from the metering device 31c through a conduit 204 toa two-pump system .39

18 like the one shown and described with reference `to Fig.- 2k, andthence to a flow divider 2|8. p e

. The term airwhen used in the claims is intended to mean anyappropriate comb ustion-supi porting medium.

We claim: n

, 1. In a power plant comprising aga's turbine, a speed responsivedevice driven at a speed pro-1 portionate to turbine speed, a burner forsupplying combustion productsto drive the gas turbine, means :forming apath for the flow of fuel to the burner, means forming a path for thenow of air to the burner, :and a flow regula tor for the lfuel pathincluding a shiftabl-e con- -trol device, and means fortransmittingtothe control device in opposition to one another forces representativeof air-flow rate andY of fuel-flow rate to shift the control device inone direction or another in accordance with a positive or negativedifference between these for-ces for making the flow regulator adjustthe fuel-now rate in maintenance of a predetermined ratio of fuel- Aflowrateeto air-now rate; the combination with the control device', of meansfor delaying the shifting thereof to produce stable operation of ythepower plant lby minimizing the effect on the .fuel-flow rate of chan-gesin the .air-flow rate of short duration, and controlled means controlledby said speed responsive device for reducing the effectiveness of theaforesaidvdelaying means during operation of the turbine inother than apredetermined speed range. l e e 2. The combination specieduin claimvl,the delaying meanscomprising` .a container foriluid hav-ing outletprovided with restriction, and the effectiveness-reducingv means for thedelaying means serving-.to remove restriction from .the outlet Yofthecont-ainer.

3. In a power `plant comprising a burner, means forming a path for theflow of .fuel to the burner, means forming a path for the flow of air tothe burner, and a now regulator for the fuel path including a shiftablepart responsive to airflow rate and fuel-flow rate for effectingshiftjof n the part to Aadjust the fuel-flow ratein'maintenance of apredetermined ratio of fuel-now rate l to air-flow rate; the combinationwith the shift- .able part, of -means for delaying the shifting thereofto produce stable operation of the power plant by minimizing the eli'ecton the fuel-*flow rate of changes in .the air-now rate of shortdur-ation, said delaying means comprising .a chamber defined by .wallstructure consisting of expansible walls movable as a unit with saidpart and `fixed oriiiced walls having v-alving associated therewith,said eXpansibl-e walls permitting ythe par-t vto take a position incorrespondence withA said. predetermined ratio at a limited ratecontrolled-solelyby the degree of oriiicial effect'allowed bysaidvvalving. y e.

4. The combination specified in claim 3, the delaying `means furthercomprising'a fuel path passage opening adjacent the valvingto providefuel for subjectingfthe valving to force of amore reincluding. a partandrmeans including 'moving walls sensitive to air-now rate and fuel-nowrate strictive tendency. y y n Y- V5. In a power plant comprising aburner, means forming a path for the flow of fuel to the burner, meansvforming a path for the ow of 'air to the burner, a Ina-chine driven byproducts of combustion of fuel and air coming fromr the burner, and aflow regulator for the fuel path for shifting the part to adjust thefuel-flow rate VVin-Inainte'n'ance of a predetermined ratio of Vfuelflowrate to air-flow rate; the combination with the ow regulator, of meansfor delaying the shif-tinglthereof to produce stable operation ofthemachine lby eliminating the effect on the fuel-flow rate of changesin the vair-flow rate of short duration, said delaying means includingfixed walls and oneV said moving wall forming an expansible liquidccntainerhaving an opening restricted so as to slow any'volume chan-geof the container by only slowly passing liquid, and means connecting themoving wall of the container and the shiftable part for causing theslowness of volume change of the container to delay shifting of theshiftablc part, and automatic means responsive 'to roperation ofthemachine in other than a desired speed range for reducing theeffectiveness of the delaying means by removing the ability of therestricted opening to slow voiume changes of the container.

6. In -a power plant comprising a burner, means forming a path for theflow of fuel to the burner,- means forminga path for the ilow of air tothe burner, and a flow regulator for the fuel path including a shiftablepart and means including moving walls sensitive to air-flow rate andfuel-flow rate for shifting the part to adjust the fuel-flow rate inmaintenance of a predetermined ratio of fuel-now rate to air-now Vrate;the c-ombination with the iiow regulator, of

means for delaying the shifting thereof to minimize the effect on thefuel-flow rate of changes in the air-flow rate-of short duration andincluding fixed walls and a said moving wall forming an eXpan-sibleliquid container having an opening Yrestricted so as to slow any volumechange of the container by only slowly passing liquid, and meansconnecting the moving wall of the container and the shiftjable part forcausing the slowness of volume change of the container to delay shiftingof the sh'iftable part.

7. In a power plant comprising a burner, means forming a path for thenow of f uel to the burner, means `forming a path for the ow of air tothe burner, and a flow regulator for the fuel path including a-shif-tablepart and vmeans responsive to 'air-now rate and fuel-flowrate for shifting the part to adjust the fuel-flow rate in maintenanceof -a predetermined ratio of fuelflow-rate to air-flow rate; thecombination with the .shiftable part, of means for delaying the shiftingthereof to produce stable operation of the power plant by minimizing theeffect on the fuel-flow rate of changes in the air-flow rate of shortduration, and means respon-sive to a large reduction in air-flow ratefor reducing the effectiveness of the delaying means.

I8. In a power plant comprising a burner, means forming a path for theflow of fuel to the burner, mean-s forming apath for the flow of 'air tothe burner, a machine driven -by products of 'combustion of fuel and aircoming from the burner, and a flow regulator for the fuel path includinga part and means responsive to airflow rate and fuel-flow rate forshifting the part to adjust the fuel-dow rate in maintenance of apredetermined ratio of fuel-flow rate to airflow rate; the combinationwith the shiftable part, of means for delaying the shifting thereof toproducestable operation of the power plant by minimizing the effect onthe fuel-flow rate of changes in the air-flow rate'of short duration,means for reducing theieectiveness of the delaying means duringoperation of the turbine in vother than a predetermined speed range,andA means-responsive to a large reduction in air-flow rate for reducingthe effectiveness of the delaying n'ieansLl'l 1 Y 1 9. In a power plantcomprising a burner, means forming a path for the flow of fuel to theburner, means forming a path for the flow of air tothe burner, a machinedriven by products of combustion -of fuel and air coming from theburner, and a flow 'regulator for the fuel -path including a part andmeans responsive to airflow rateand fuel-'flow rate for shifting thepart to adjust the fuel-flow rate in maintenance of a predetermined-ratio of fuel-flow ra-te vtoair-iiow rate; the combination `with theshiftable part; of means ford-elaying the shifting thereof to producestable operation of the mach-ine by minimizing the effect on thefuel-flow rate of changes in the air-how rate o-f short duration, saiddelaying means comprising an emiansibleA liquid container havingl anopening restricted soas to slow any volume'change of the container byonly slowly passing liquid, and means connecting the container and theshiftable part for causing the slowness lof volume change of thecontainer to delay shifting of the shiftable part, and means responsiveto operation of the machine in other than a desired speed range forreducingthe effectiveness of the delaying means by removing the abilityof the restricted opening to slow volurne changes of the container. t

l0. In a power plant comprising a burner, means forming a path for the:dow of fuel to the burner, means forming a path for the flow of air tothe burner, means forming a metering orice in the fuel path,v meansforming a regulating orifice in the fuelpath and including a partshift'ablerfor adjustment of the size of the regulating orifice, air andfuel diaphragms connected With the shiftable part, means fortransmittingy to opposite sides of the air diaphragm air pressureshaving a difference indicative of air-flow rate in the air path, andmeans for transmitting to opposite sides of the fuel diaphragm meteredand unmetered fuel pressures at the sides of the metering orice, theshiftablc part being shifted in .accordance with the difference betweenthe aforesaid air-pressure differ-ence Aand the vafore- Saidfuel-pressure difference for maintaining a given ratio of fuel-flow'rateto 'air-flow rate, 'the combination therewith, of means for delaying4shifting of the shiftable part to produce stable opera-tion of thepower plant by minimizing the effect on the fuel-now rate of changes inthe air-flow rate of short duration, vsaid delaying means comprising anexpansible container'for fuel having an opening connected with the fuelpath on the metered side of the metering orifice and restricted so as toslow any volume change by only slowly passing fuel, and means connectingthe container, the air and fuel diaphragme, and the shiftable part tocause the slowness of volume change of the container to produce theaforesaid delay in shifting of the shiftable part, means responsive tooperation of the machine in other than a desired speed ran-ge forreducing the effectiveness of the delaying means by removing the abilityof the restricted opening to slow volume changes of the container, 'adiaphragm forming a wall of the container, and means for connecting thediaphragm side outward of the container to the fuel path on theunmetered side o f the metering orifice,` whereby a large change inair--iiow rate immediately changes thefuelflow rate by causing theshiftable part to act through an attempted volume change ofthe'container to raise the fuel pressure of the container to the:unmetered fuel pressure on the outward .sidelof theV container diaphragmand thereby to move the. latter to accommodate. shifting ofthe'.-shiftable part without change involume of .the

'.container.

" F11'. In -a power plant comprising a .burn-er,

means forminga path for the iiow of `fuel to the burner, means formingapat-hlfor the flow of .air

the burner, means forming a metering orice in the fuel path, meansforming a regulating orice in the fuel path and including a partlshifta- Hble forfadjustment of the size ofthe regulating 'ori'iice air-and'fu'el diaphragins connectedwith the Shiftable part,A means fortransmittingto `opposite sides of theair diaphragm air pressures'-having a `difference indicative of air-flow ratei-n the air path, andmeans for transmitting to opposite sides of the'f-uel diaphragm meteredand "unmet-ered fuel pressures prevailing at the sides of th-emeteringorifice,v the shiitable par-t being Vshifted.v in accordance with theV'difference between the laforesaid. air-pressure difference'a'ndVthe"aforesaid` fuel-pressure kdiffrer-ice for maintaining Ia "givenratio of fuel-now rat-e to yairvflow rat-e, the combination therewith,`ofrneans -for delaying shifting of the lshiftab'leY part to producestable operation of the powerv plant by ,minimizing the effect on the.fuel-flow rate of rchanges in the air-flow rate of short-duration,saiddelaying means compri-sing an expansible container for-'fuel havingan opening connected vwiththe'fuelhpvath on the meteredside ofthemetering'orice and restricted so ai-s to slowany rvVolume change by onlyslowly vpassing fuel, and

means connecting the container, therairand fuel diaphragms andtheshiftable parttn cause the slowness ofyolume Vchange of the container toproduce the aforesaid delay in Vshifting of the shit-table part, meansresponsive to operation of the machine in other than .a desired speedrange for reducing the effectiveness of the delaying means Ybyv'removing' the ability of the restricted opening to slowvolumechanges'of the container, ;a" diaphragm forming a wall of thecontainer, 'meansjr connecting the diaphragmside noutwardof thecontainer to the fuel pathfon'the unmetered side of the meteringorifice, whereby a large decreaseinair-flow rate immediately decreasesthe fuel-flow rate bly causing the air diaphragm to act through anattempted volume fle- Vcrease of the container to raise the fuelpressure of the container above the unmetered fuel pressure von theoutward sideof thecontainer diaphragmand thereby to move the latter toVac- "side'of' the orifice, means forming aV regulatingV y,orifice inthefuel path and including a shit-table part, and means for transmitting tothe shiftable vpart in opposed relation a force proportional to the-differencebetween -unmetered and metered fuel pressures as a measure offuel-flow rate and vaforce indicative of air-flow rate to shift theshiftable part in maintenace of a givenratio of 22 fuel-flow to air-flowrate, .the Lcombination there'- Wi'th, of. means for delaying shiftingof thlezshftfable part .Y to produce. stable operation ofY the powerplant by minimizing the effect on the fuelow rate 'of chan-ges in theair-'flow rate of short duration, said delaying means .comprising anexpansible container havingfan opening connected with the metered fueland restricted so as to slow any volume change by only slowlypassing'fuel. and means connecting the container i yand the shiftablepart to cause the slowness of volume change ofthe container to produceslowness in shifting of the shiftable part, the container havling amovable wall, and means for subjecting the outer .side of themovablewall to unmetere-d fuel pressure, whereby lza large decrease in air-nowrate immediatelyA decreases the fuel-flow rate `by causing theshif-ta-ble: part in response to the change in air force transmitted tothe shiftable partv to acty through an attempted volume decrease of thecontainer to raise the value of the fuel pressure of the container frommetered. fuel pressure to the `unmetered fuel. pressure' on the outerside of the container wall and thereby to move .the lattertowac'commo-d'ate shifting ofthe shiftable parl-without change in volumeof the container.. a Y .i ,Y l: Y 13. In -a power` plant comprising vaburner,

meansforming a path for the ow of fuel tothe burner, means forming aregulating orice' in the fuel path and including a shiftablepart, meansfor shifting the shiftable Apart in'accordance' with `a difference inforces indicative of fuel-nowrate and air-flow Vrate in said vfuelandair paths'in --order to maintain a given ratio 'of airelow: rate tofuel-fiow rate, the combination therewith, of means for delaying theshifting'ofthe shiftable part toproduce stable operationzof the'ipowerplant by minimizing the effect onthe. fuel-now rate of changes in thekair-,flow `rateof short duration, said delaying meansi comprising anexpansible container having' 'an opening Connected with thev fuel pathandrestrcted` for Islow- `ing-volume:changes of the container by passingoppose `opening of the valve, and means transmitting to the valve aforce `varying with air-.ow

ratey tol oppose. opening of the valve. 1

.14.\. fn a'power plant, the combination `specified in claim ,i3 andfurther comprising meansffor providing an Yunrestricted 'opening in the`container in response cooperation ,of the power plant in other than apredetermined.'speedrange.'` 1

l5.. In a Apower .plant comprising a burner, means forming a' pathV forthe .flow of air to the bintner, means forming a path ,for the flow offuel to theibnrner, .andmeans for :regulating fuel flow to maintain zapredeternnnedfratioyof fuel flow rate .to airgiiow rate; the combinationtherewith,

.of means for delaying the responsiveness'of the regulating means toproduce stableoperationy of the powerplant by minimizing the veffect onthe fuel-flow rate of changes in the aireflow rateof :short duration,and' including valveecontrolled vfluid-confining-means adapted toconfina-.a mass of dam-ping fuel, and automatic means forauto- 23matically opening the valve of the last said valvecontrolled means forreducing the effectiveness of the delaying means in response tooperation of the power plant in other than a predetermined range.

16. In. a power plant comprising av burner,

'means forming av path for the flow of air to the burner, means forminga path fo-r the flow of fuel tothe burner, and means for regulating fuelflow tozmaintaina predetermined ratio of fuel-flow rate to air-flowrate; the combination therewith, of means for delaying responsiveness ofthe ,regulating means to produce stabe operation of .the power plant byminimizing the effect on the fuel'- iiow'rate of changes in the air-flowrate of short duration, and 'means for modifying the action of thedelaying means to make the regulating means immediately responsive to alarge change in airflow rate.

17. In a power plant comprising a burner, means forming apath for theflow of air to the burner, means forming a path for the flow of fuel vtothe burner, 'and means for regulating fuel flow to maintain apredetermined ratio of fuel-flow rate to air-flow rate; the combinationtherewith,

of means for delaying responsiveness of the regulating means to producestable operationof the power plant by minimizing the effect on thefuelimmediately responsive to a large changeV in airflow rate. i

=xl8. In a power plant comprising a burner,

`means forming a path for the flow of air to the burner, means forming apath for the iiow of fuel to lthe burner, means forming a regulatingorifice -in the fuel path and including a shiftable part,

and means for shifting the shiftable part in accordance with variationfrom a predetermined Value of the ratio of fuel-flow. rate to air-flowrate in order to maintain the ratio at the said predetermined value, thecombination therewith,

of means for delaying the shifting of the shiftable part to producestable operation of the power plant by minimizing effects on fuel-flowrate of changes in air-dow rate of short duration, said delaying meanscomprising an expansible container having an opening connected with thefuel path and restricted for slowing change in the volume of thecontainer by passing fuel only slowly, and means for connecting thecontainer and the shiftable part, and means for preventing the delayingmeans from interfering with immediate shifting ofthe shiftable part inresponse to a large reduction in air-flow rate, said last mentionedmeans comprising a movable wall associ-- ated with the container meansfor transmitting pressure of the fuel path to the exterior of the wall,and resilient means acting against the wa to oppose outward movementthereof.

19.'1n a power plant comprising a burner, means forming a path for theflow of air to the burner, means forming a path for the flow of fuel tothe burner, means forming a regulating orice in the fuel path andincluding a Ashiftable part, and means for shifting the shiftable partin accordance with variation from a predetermined value of the ratio offuel-flow rate to airflow rate in order to maintain the ratio at thesaid predetermined value, the combination therewith, of means fordelaying the shifting, of the 24 shiftable part to produce stableoperation of the power plant by minimizing effects on fuel-flow rate ofchanges in air-flow rate of short duration, said delaying meanscomprising an expansible container having an opening connected'with thefuel path and restricted for slowing change in the volume of thecontainer by passing fuel only slowly, and means for connectingl thecontainer and the shiftable part, and means for preventing the delayingmeans from interfering with immediate shifting ofthe shiftable part inresponse to a large reduction in air-flow rate, said last mentionedmeans comprising amovable wall associatedwith the container, means fortransmitting pressure of the fuel path to the exterior of the wa-ll,means forming a chamber on the outer side .of the wall, means fortransmitting pressure of the fuel path to the chamber and to theexterior of the movable wall, resilient means acting between the movablewall anda portion of the chamber opposite the movable wall to opposeoutward movement thereof, andmeans loosely connecting the movable walland the said opposite chamber portion to limit inward movement of themovable wall while permitting outward moveyment thereof.

.to unmetered fuel pressure in the fuel pathl above the metering orificeand on the other side to metered fuel in the fuel path below themetering orifice, whereby the shiftable part is shifted to adjust thefuel-flow rate in maintenance of a predetermined ratio of fuel-flow rateto air-how rate; the combination therewith, of means forming with themetered-fuel-pressure side of the fuel diaphragm a container. having arestricted opening adapted by only slowly passing fuel to slow volumechange of the' container and movement of the diaphragm and thereby toproduce stable operation ofthe power plant by minimizing the effect onthe fuel-iiow rate of change in the air-dowl rate of short duration.

21. In a power plant, the combination specified invclaim 20 and furthercomprising means responsive to operation of the power plant in otherthan the desired speed range for providing an unrestricted opening inthe container thereby to reduce the effectiveness of the restrictedopening in slowing volume change of the container and movement of thediaphragm.

`PAUL R. voGT. PAUL T. NIMS,

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 2,384,282 Chandler Sept. 4, 19452,409,446 Pavlecka et al Oct. 15, 1946 2,423,183 Forsyth July l, 1947'2,457,595 Orr, Jr Dec. 28, 1948 r FOREIGN PATENTS Number Country Date493,174 Great Britain Oct. 4, 1938

